The vibrational transition of the deuterium impurity in a solid parahydrogen crystal has been studied using an ultrahigh resolution color center laser spectrometer. The laser was locked to a temperature-stabilized external cavity and had a spectral purity of 0.5 MHz. In the previous work of Chan. Xu, Gabrys, and $Oka^{1}$, many sharp transitions had been observed in the deuterium impurity Q-branch vibrational spectrum. A few of the transitions showed a linewidth (HWHM) of 7 MHz. The assignment of the $Q_{1}$(0) spectral features was unclear because this transition can be induced by either a neighboring J=1 deuterium or a neighboring J=1 hydrogen and the previous crystal contained both of these impurities. Also, some of the deuterium $Q_{1}$ (1) transitions could fall in the $Q_{1}$ (0) region. By varying the J=1 hydrogen and the J=1 deuterium concentrations, we have been able to assign the features of the $Q_{1}$ (0) and the $Q_{1}$(1) transitions. We have also observed striking polarization dependences of these features. At higher J=0 deuterium concentration, the $Q_{1}(0)$ features had the characteristic asymmetric exciton lineshapes. when the J=0 deuterium concentration was reduced, these lines narrowed and gained symmetric lineshapes. When the J=1 concentration was then also reduced, the $Q_{1}(0)$ lines narrowed further and linewidths of 2 MHz HWHM were observed. The features of the $Q_{1}$(1) transition also showed strong concentration and polarization dependences. At high J=1 deuterium concentration, we observed a broad($\sim$250 MHz HWHM) single molecule transition as well as the nearest neighboor pair transitions. With reduced J=1 hydrogen and J=1 deuterium concentrations, the single molecule transition narrowed by more than an order of magnitude and showed a splitting of -10 MHz whose exact magnitude was polarization dependent.